Liquid ejection head and liquid ejection device

ABSTRACT

A liquid ejection head includes first and second recording element boards having recording elements for generating energy to be utilized for ejection of liquid, first and second support members for respectively supporting the first and second recording element boards, and a flow channel forming member carrying thereon the first and second support members arranged side by side. The edge of the first recording element board located at the side of the second recording element board projects toward the second recording element board from the edge of the first support member located at the side of the second support member.

BACKGROUND OF THE INVENTION Field of the Invention

Liquid ejection devices such as inkjet printers are being employed notonly for home use printing but also for commercial printing such asbusiness use printing and retail photo printing, and for industrialprinting applications including electronic circuit drawing and paneldisplay manufacturing. High speed printing capabilities are stronglyrequired for liquid ejection devices, particularly in the field ofbusiness use printing. Efforts are being made to realize commerciallyviable line type liquid ejection heads that have a width greater thanthe widths of recording mediums to be used with the heads and hence agreater number of liquid ejection ports than ever in order to achievehigher speed printing.

Liquid ejection heads to be formed by arranging a plurality of recordingelement boards, each having a plurality of ejection ports, in thelongitudinal direction of the liquid ejection head have been proposed astechniques for realizing liquid ejection heads having a broader width.

The specification of Japanese Patent No. 4,495,762 discloses a techniqueof arranging a plurality of recording element boards in a row in thelongitudinal direction of a liquid ejection head. The specification ofJapanese Patent No. 4,824,795 describes a technique of preparing aplurality of ejection modules, each having a recording element board anda support member supporting the recording element board, and mountingthe plurality of ejection modules on a supporting plate in a state wherethe ejection modules are individually dismountable. With this technique,if a specific one of the ejection modules falls into trouble, only themodule in trouble can be replaced.

When ejection modules are arranged in a row in a condition where theyare individually dismountable by using either the technique described inthe specification of Japanese Patent No. 4,495,762 or the one describedin the specification of Japanese Patent No. 4,824,795, the minimaldistance between any two adjacently located recording element boards islimited by the levels of processing accuracy and of mounting positionalignment accuracy of the support members because these accuracy levelsare low. This problem can give rise to instances where the distancebetween any two adjacently located recording element boards cannotsatisfactorily be reduced.

When the distance separating any two adjacently located recordingelement boards cannot be made satisfactorily short, the width ofdisplacement of the rows of ejection ports arranged on the two recordingelement boards in neighboring areas can become remarkably large asviewed in the scanning direction and the gap separating the rows ofejection ports arranged on the two recording element boards can becomeintolerably large as viewed in the longitudinal direction. Then, as aresult, the recorded image obtained by using a liquid ejection headhaving such drawbacks can represent unevenness on the recorded image inareas that correspond to neighboring areas of recording element boards.

SUMMARY OF THE INVENTION

In view of the above-identified problems of the prior art, the object ofthe present invention is therefore to provide a liquid ejection head anda liquid ejection device in which the distance between any twoadjacently located recording element boards can be reduced more thanever.

According to the present invention, there is provided a liquid ejectionhead including: first and second recording element boards havingrecording elements for generating energy to be utilized for ejection ofliquid; first and second support members for respectively supporting thefirst and second recording element boards; and a flow channel formingmember carrying thereon the first and second support members arrangedside by side, wherein the edge of the first recording element boardlocated at the side of the second recording element board projectstoward the second recording element board from the edge of the firstsupport member located at the side of the second support member.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of the liquid ejection device of UseExample 1 of the present invention, schematically representing theconfiguration thereof.

FIG. 2 is a schematic illustration of the first circulation route in UseExample 1 of the present invention.

FIG. 3 is a schematic illustration of the second circulation route inUse Example 1 of the present invention.

FIGS. 4A and 4B are schematic perspective views of the liquid ejectionhead of Use Example 1 of the present invention, schematicallyrepresenting the configuration thereof.

FIG. 5 is an exploded schematic perspective view of the liquid ejectionhead of Use Example 1 of the present invention.

FIGS. 6A, 6B, 6C, 6D, 6E and 6F are surface views of the flow channelforming member in Use Example 1 of the present invention.

FIG. 7 is an enlarged schematic perspective see-through view of the flowchannel forming member of Use Example 1 of the present invention,representing flow channels in the inside.

FIG. 8 is a schematic cross-sectional view taken along line 8-8 in FIG.7.

FIGS. 9A and 9B are schematic illustrations of an ejection module in UseExample 1 of the present invention.

FIGS. 10A, 10B and 10C are schematic plan views of a recording elementboard in Use Example 1 of the present invention.

FIG. 11 is a schematic perspective view of the recording element boardand the lid member illustrated in cross section taken along line 11-11in FIG. 10A.

FIG. 12 is an enlarged schematic plan view of a neighboring area of tworecording element boards of Use Example 1 of the present invention.

FIGS. 13A and 13B are schematic perspective views of the liquid ejectionhead of Use Example 2 of the present invention, schematicallyrepresenting the configuration thereof.

FIG. 14 is an exploded schematic perspective view of the liquid ejectionhead of Use Example 2 of the present invention.

FIGS. 15A, 15B, 15C, 15D and 15E are surface views of the flow channelforming member in Use Example 2 of the present invention.

FIG. 16 is a schematic perspective see-through view of a recordingelement board and a flow channel forming member of Use Example 2 of thepresent invention, representing the connection relationship thereof fromthe viewpoint of liquid flowing through them.

FIG. 17 is a schematic cross-sectional view taken along line 17-17 inFIG. 16.

FIGS. 18A and 18B are schematic illustrations of an ejection module inUse Example 2 of the present invention.

FIGS. 19A, 19B and 19C are schematic plan views of a recording elementboard in Use Example 2 of the present invention.

FIG. 20 is a schematic perspective view of the liquid ejection device ofUse Example 2 of the present invention, schematically illustrating theconfiguration thereof.

FIGS. 21A and 21B are schematic perspective views of the liquid ejectionhead according to the first embodiment of the present invention,schematically illustrating the configuration thereof.

FIGS. 22A, 22B, 22C, and 22D are schematic top views of the liquidejection head according to the first embodiment of the presentinvention.

FIGS. 23A and 23B are schematic illustrations of the positionaldisplacement of some of the rows of ejection ports of the liquidejection head according to the first embodiment of the presentinvention.

FIG. 24 is a schematic cross-sectional lateral view of a neighboringarea of two adjacently located recording element boards according to thefirst embodiment of the present invention.

FIGS. 25A, 25B, 25C and 25D are schematic illustrations of some of theadvantages of the liquid ejection head according to the first embodimentof the present invention.

FIGS. 26A and 26B are schematic perspective views of the liquid ejectionhead according to the second embodiment of the present invention,schematically illustrating the configuration thereof.

FIGS. 27A and 27B are schematic views of some of the recording elementboards arranged side by side according to the second embodiment of thepresent invention.

FIG. 28 is a flowchart, illustrating the steps of manufacturing theliquid ejection head according to the second embodiment of the presentinvention.

DESCRIPTION OF THE EMBODIMENTS

Now, the present invention will be described in greater detail by way ofuse examples and embodiments of the present invention and by referringto the accompanying drawings. Note, however, that the description givenbelow by no means limits the scope of the present invention. The liquidejection heads of the embodiments that are described below are realizedby using thermal type recording elements that are heat generatingelements designed to generate air bubbles to eject liquid, althoughpiezoelectric type or some other liquid ejection type recording elementsmay alternatively be employed for the purpose of the present invention.A liquid ejection head for ejecting liquid such as ink according to thepresent invention and a liquid ejection device including such a liquidejection head can find applications in the field of printers, copyingmachines, facsimile machines having a telecommunication system and wordprocessors having a printer section. Furthermore, they also can findapplications in the field of industrial recording apparatus formed bycompositely combining a liquid ejection device according to the presentinvention with any of various processing devices. For example, they canfind applications in the field of producing biochips, in the field ofelectronic circuit printing, in the field of semiconductor substrateproduction and so on.

While a mode of realization of the present invention where liquid suchas ink is made to circulate between a storage tank and a liquid ejectionhead is adopted in each of the Use Examples that will be describedbelow, any other mode of realization of the present invention mayalternatively be adopted. In a different mode of realizing the presentinvention, for example, the liquid ejection head may be provided withtwo storage tanks and one of them is arranged at the upstream side whilethe other one is arranged at the downstream side of the liquid ejectionhead and liquid is made to flow from the upstream side one of the tanksto the downstream side one in order to cause the liquid in the pressurechambers of the liquid ejection head to flow without causing the fluidto circulate.

In each of the Use Examples that will be described below, a so-calledline type (page wide type) liquid ejection head having a length thatcorresponds to the width of the recording medium to be used with theliquid ejection head is adopted. However, a so-called serial type liquidejection head designed to execute a recording operation while it isscanning the recording medium to be used for the recording operation mayalternatively be adopted. An exemplar serial type liquid ejection headis typically but non-limitatively mounted with recording element boardsincluding a recording element board for black ink and recording elementboards for respective color inks. Alternatively, a serial type liquidejection head may include a plurality of recording element boards thatare arranged such that the rows of ejection ports thereof partly overlapin the direction of the rows of ejection ports and have a width greaterthan the width of the recording medium to be used with the liquidejection head.

(Use Example 1)

(Explanation of the Inkjet Recording Apparatus)

FIG. 1 is a schematic illustration of the liquid ejection device of UseExample 1, schematically representing the configuration thereof that canbe realized by applying the present invention. The liquid ejectiondevice illustrated in FIG. 1 is an inkjet recording apparatus 1000 (tobe also referred to simply as recording apparatus hereinafter). Therecording apparatus 1000 includes a conveying section 1 for conveyingrecording mediums 2 and a line type liquid ejection head 3 arrangedsubstantially orthogonal relative to the direction in which a recordingmedium 2 is conveyed and is designed as a one-pass recording apparatusthat continuously executes recording operations with a single pass,while conveying the recording mediums 2 continuously or intermittently.The recording medium 2 may be in the form of a roll of paper or in theform of sheets of paper. The liquid ejection head 3 can operate for fullcolor printing, using CMYK inks (cyan ink, magenta ink, yellow ink andblack ink) as liquid. As will be described hereinafter, the liquidejection head 3 is fluidically connected to liquid supply means whichare supply channels for supplying the liquid ejection head with liquidas will be described hereinafter, main tanks and buffer tanks (see FIG.2). The liquid ejection head 3 is additionally electrically connected toan electric control section that transmits electric power and logicsignals to the liquid ejection head 3. The liquid flow route and theelectric signal transmission route in the liquid ejection head 3 will bedescribed hereinafter.

(Explanation of the First Circulation Route)

Now, the circulation routes for circulating liquid that are applied tothe recording apparatus of this Use Example will be explained below.FIG. 2 is a schematic illustration of the first circulation route forcirculating liquid, representing a mode of realization of circulationroute applicable to the recording apparatus of this Use Example.Referring to FIG. 2, the liquid ejection head 3 is fluidically connectedto first circulation pump (high pressure side) 1001, first circulationpump (low pressure side) 1002 and buffer tank 1003. While only the routethrough which one of CMYK inks flows is illustrated in FIG. 2 for thepurpose of simplification, in reality a total of four sets ofcirculation routes for inks of the four colors are arranged in theliquid ejection head 3 and the recording apparatus 1000 main body.

The buffer tank 1003, which is provided so as to operate as sub-tank, isconnected to main tank 1006. The buffer tank 1003 has an aircommunication port (not illustrated) for establishing communicationbetween the inside of the tank and the atmosphere so as to discharge airbubbles in the ink in the buffer tank to the outside. The buffer tank1003 is additionally connected to replenishment pump 1005. When liquidis consumed in the liquid ejection head 3 as a result of an operation ofejecting or discharging liquid from the ejection ports of the liquidejection head 3, the replenishment pump 1005 operates to transfer inkfrom the main tank 1006 to the buffer tank 1003 to compensate theconsumed amount of ink. Operations of ejecting and discharging liquidtypically include recording operations and suction recovery operations.

The two first circulation pumps 1001 and 1002 that are liquidtransportation means have a function of drawing liquid from liquidconnection sections 111 of the liquid ejection head 3 and flowing itdown to the buffer tank 1003. The first circulation pumps are preferablypositive displacement pumps that are capable of quantitatively feedingliquid. More specifically, pumps that may preferably be selected for thefirst circulation pumps include tube pumps, gear pumps, diaphragm pumpsand syringe pumps. For example, they may be of the type having aconstant flow rate valve and a relief valve that are popularly known andarranged at the pump outlet so as to secure a constant flow rate. Whenthe liquid ejection head 3 is driven to operate, liquid is made to flowat a constant flow rate through common supply channel 211 and commoncollection channel 212 respectively by the first circulation pump (highpressure side) 1001 and the first circulation pump (low pressure side)1002. The liquid flow rate is preferably so selected as to be foundabove the flow rate level below which the temperature differences amongthe recording element boards 10 in the liquid ejection head 3 adverselyaffect the quality of the images recorded by the inkjet recordingapparatus. However, if a too large flow rate is selected, the negativepressure differences among the recording element boards 10 become toolarge under the influence of the pressure loss in the flow channels inthe liquid ejection head 3 to give rise to a problem of uneven densityon the recorded image. Therefore, the flow rate is preferably selectedby taking both the temperature differences and the negative pressuredifferences among the recording element boards 10 into consideration.

Negative pressure control unit 230 is arranged between secondcirculation pump 1004 and liquid ejection unit 300. The negativepressure control unit 230 operates such that, when the flow rate in thecirculation route fluctuates due to a recording duty difference, itconfines the pressure at the downstream side of the negative pressurecontrol unit 230 within a predetermined range that is centered at apreselected and desired pressure level. The downstream side of thenegative pressure control unit 230 is the side located closer to theliquid ejection unit 300 than to the negative pressure control unit 230.The negative pressure control unit 230 has two pressure regulators inwhich mutually different respective control pressures are preselectedand preset. The two pressure regulators are not subjected to anyparticular limitations provided that each of them can control thepressure at the downstream side thereof so as to confine anyfluctuations of the pressure within a predetermined range that iscentered at a preselected and desired pressure level. So-called“pressure reducing regulators” may be adopted for the pressureregulators. When pressure reducing regulators are employed for thepressure regulators, pressure is preferably applied to the upstream sideof the negative pressure control unit 230 by means of the secondcirculation pump 1004 and by way of liquid supply unit 220 asillustrated in FIG. 2. Such an arrangement can raise the degree offreedom of laying out the buffer tank 1003 in the recording apparatus1000 because the arrangement can suppress the influence of the headpressure of the buffer tank 1003 on the liquid ejection head 3. Thesecond circulation pump 1004 is only required to represent head pressurenot lower than a predetermined pressure level within the range of flowrate of circulating ink that is observed when the liquid ejection head 3is driven to operate. For example, a turbo pump or a positivedisplacement pump may be used for the second circulation pump 1004. Morespecifically, a diaphragm pump may be selected for the secondcirculation pump 1004. Alternatively, the second circulation pump 1004may be replaced by a water header tank that is so arranged as torepresent a predetermined water head difference relative to the negativepressure control unit 230.

With regard to the two pressure regulators, the pressure regulator inwhich relatively higher output pressure is preselected and the pressureregulator in which relatively low output pressure is preselected arerespectively connected to the common supply channel 211 and the commoncollection channel 212 in the liquid ejection unit 300 by way of theinside of the liquid supply unit 220. In FIG. 2, the pressure regulatorwith relatively high preselected output pressure is indicated by H,whereas the pressure regulator with relatively low preselected outputpressure is indicated by L. The common supply channel 211, the commoncollection channel 212, individual supply channels 213 that communicatewith respective recording element boards and individual collectionchannels 214 that also communicate with respective recording elementboards are arranged in the liquid ejection unit 300. The individualsupply channels 213 and the individual collection channels 214respectively communicate with the common supply channel 211 and thecommon collection channel 212. Due to this arrangement, part of theliquid that flows through the common supply channel 211 then flows fromthe common supply channel 211 to the common collection channel 212 byway internal flow channels in the inside of the recording element boards10 (as indicated by arrows in FIG. 2). This is because the pressureregulator H with relatively high preselected output pressure isconnected to the common supply channel 211 and the pressure regulator Lwith relatively low preselected output pressure is connected to thecommon collection channel 212 to consequently give rise to a pressuredifference between the two common channels (the common supply channel211 and the common collection channel 212).

As described above, in the liquid ejection unit 300, liquid flowsthrough both the common supply channel 211 and the common collectionchannel 212 so as to give rise to flow paths in the respective recordingelement boards 10 through which part of the liquid flows. Then, as aresult, the heat generated in the recording element boards 10 can bedischarged to the outside of the recording element boards 10 by means ofthe part of the liquid that flows through the common supply channel 211and the common collection channel 212. Additionally, with theabove-described arrangement, while the liquid ejection head 3 is beingdriven for a recording operation, liquid is made to flow through theejection ports and the pressure chambers that are not in operation so asto suppress any possible rise of ink viscosity that can take place atthose sites. Additionally, liquid with increased viscosity and foreignobjects contained in the liquid, if any, can be discharged to the commoncollection channel 212. Thus, this arrangement allows the liquidejection head 3 of this Use Example to record high quality images athigh speed.

(Explanation of the Second Circulation Route)

FIG. 3 is a schematic illustration of the second circulation route inUse Example 1 of the present invention, which differs from theabove-described first circulation route but also can be applied to arecording apparatus according to the present invention. The secondcirculation route differs from the first circulation route mainly inthat both of the two pressure regulators of the negative pressurecontrol unit 230 control the pressure at the upstream side of thenegative pressure control unit 230. In other words, both of the twopressure regulators operate to confine the pressure at the upstream sideof the negative pressure control unit 230 within a predetermined rangethat is centered at a preselected and desired pressure level (just likethe operation of so-called “back pressure regulators”). The secondcirculation route also differs from the first circulation route in thatthe second circulation pump 1004 operates as negative pressure sourcefor reducing the pressure at the downstream side of the negativepressure control unit 230. The second circulation route additionallydiffers from the first circulation route in that both of the firstcirculation pump (high pressure side) 1001 and the first circulationpump (low pressure side) 1002 are arranged at the upstream side of theliquid ejection head and the negative pressure control unit 230 isarranged at the downstream side of the liquid ejection head.

At the second circulation route, the negative pressure control unit 230operates to confine the pressure fluctuations that arise at the upstreamside of itself within a predetermined range that is centered at apreselected and desired pressure level even when the flow rate in thecirculation route fluctuates due to a recording duty difference. Theupstream side of the negative pressure control unit 230 is the side thatis closer to the liquid ejection unit 300 than to the negative pressurecontrol unit 230. As seen from FIG. 3, the pressure at the downstreamside of the negative pressure control unit 230 is preferably reduced bymeans of the second circulation pump 1004 and by way of the liquidsupply unit 220. Such an arrangement can raise the degree of freedom oflaying out the buffer tank 1003 in the recording apparatus 1000 becausethe arrangement can suppress the influence of the head pressure of thebuffer tank 1003 on the liquid ejection head 3. The second circulationpump 1004 may be replaced by a water header tank that is so arranged asto represent a predetermined water head difference relative to thenegative pressure control unit 230.

As illustrated in FIG. 3, the negative pressure control unit 230 has twopressure regulators in which mutually different respective controlpressures are preselected and preset as in the instance of the firstcirculation route. With regard to the two pressure regulators, thepressure regulator (H) with relatively high preselected output pressureand the pressure regulator (L) with relatively low preselected outputpressure are connected respectively to the common supply channel 211 andthe common collection channel 212 in the liquid ejection unit 300 by wayof the inside of the liquid supply unit 220. Due to the provision of thetwo negative pressure regulators, the pressure in the common supplychannel 211 is higher relative to the pressure in the common collectionchannel 212. For this reason, part of the liquid that flows through thecommon supply channel 211 then flows from the common supply channel 211to the common collection channel 212 by way individual supply channels213, the flow channels in the inside of the recording element boards 10and the individual collection channels 214 (as indicated by arrows inFIG. 3). As described above, the second circulation route can produceliquid flows in the liquid ejection unit 300 just like the firstcirculation route and additionally provides advantages that aredifferent from those of the first circulation route as will be describedbelow.

The first one of the advantages is that dusts and other foreign objectsproduced from the negative pressure control unit 230 can scarcely flowinto the liquid ejection head because the negative pressure control unit230 is arranged at the downstream side of the liquid ejection head 3 inthe instance of the second circulation route. The second one of theadvantages is that, in the instance of the second circulation route, themaximum value of the flow rate necessary to supply liquid from thebuffer tank 1003 to the liquid ejection head 3 is smaller than thecomparable flow rate in the instance of the first circulation route. Thereason for this will be described below.

When the liquid ejection unit 300 is in a recording standby state andhence it is not ejecting any liquid, liquid needs to be made to flow inthe common supply channel 211 and also in the common collection channel212 in order to reduce the temperature differences among the recordingelement boards 10 in the liquid ejection unit 300. Assume here that theminimum value of the sum of the flow rate of the liquid flowing in thecommon supply channel 211 and the flow rate of the liquid flowing in thecommon collection channel 212 necessary to confine the temperaturedifferences among the recording element boards 10 in the liquid ejectionhead 3 within a desired temperature range, or the minimum circulationflow rate, is A. Also assume that the ejection flow rate in an allejection state where the liquid ejection unit 300 ejects ink from all ofthe ejection ports thereof is F. Then, with the first circulation route(in the instance of FIG. 2), the preselected flow rate of the firstcirculation pump (high pressure side) 1001 and that of the firstcirculation pump (low pressure side) 1002 is equal to the minimumcirculation flow rate A. Therefore, the liquid supply rate necessary tosupply liquid to the liquid ejection head 3 in an all ejection state isequal to A+F. Thus, the maximum value of the necessary supply flow rateat the first circulation channel is equal to A+F.

With the second circulation route (in the instance of FIG. 3), on theother hand, the liquid supply rate necessary to supply liquid to theliquid ejection head 3 in a recording standby state is equal to A andthe liquid supply rate necessary to supply liquid to the liquid ejectionhead 3 in an all ejection state is equal to F. Thus, the sum of thepreselected flow rate of the first circulation pump (high pressure side)1001 and that of the first circulation pump (low pressure side) 1002 isequal to either A or F, which is larger than the other one. Therefore,the maximum value of the necessary supply rate at the second circulationroute is equal to either A or F, which is larger than the other one.

Accordingly, when two liquid ejection heads 3 having the sameconfiguration but one of them employs the first circulation route andthe other employs the second circulation route, are compared, themaximum value of the necessary supply rate for the liquid ejection head3 using the second circulation route (A or F) is inevitably smaller thanthe maximum value of the necessary supply rate using the firstcirculation route (A+F). Therefore, the degree of freedom of selectionof applicable circulation pump at the second circulation route is higherthan the comparable value at the first circulation route. In otherwords, a low cost circulation pump having a simple configuration may beput to use and/or the load of the cooler (not illustrated) to beinstalled at the main body side route may be reduced to provide anadvantage of reducing the cost of the recording apparatus main body.This advantage will be particularly remarkable at a line type liquidejection head whose A value or F value is relatively large and moreparticularly remarkable at a line type liquid ejection head having alarge longitudinal length.

On the other hand, however, there are instances where the use of thefirst circulation route is more advantageous than the use of the secondcirculation route. For example, when the second circulation route isadopted, the flow rate of the liquid flowing in the liquid ejection unit300 becomes maximum in a recording standby state and hence the lower therecording duty for the image to recorded, the higher the negativepressure applied to the ejection ports. Therefore, particularly when thechannel width (the transversal length of the channel in the directionorthogonal to the direction in which liquid flows) of the common supplychannel 211 and that of the common collection channel 212 are reduced toreduce the width of the liquid ejection head (the length of the liquidejection head in the transversal direction), high negative pressure isapplied to the ejection ports at the time of recording an image of lowrecording duty where unevenness of the image tends to become remarkable.Then, the influence of so-called satellite droplets can becomesignificantly large. When, on the other hand, the first circulationroute is adopted, high negative pressure is applied to the ejectionports only at the time of recording an image of high recording duty sothat, if satellite droplets are produced, they are hardly visible toeyes. Then, the first circulation route provides an advantage that theadverse effect of satellite droplets on the recorded image is minimal.

Thus, a preferable one of the first circulation route and the secondcirculation route may be selected depending on the specification of theliquid ejection head and that of the recording apparatus main body(including the specified value of the ejection flow rate F, thespecified value of the minimum circulation flow rate A and the specifiedchannel resistance value in the liquid ejection head).

(Explanation of the Configuration of the Liquid Ejection Head)

Now, the configuration of the liquid ejection head 3 of Use Example 1will be described below. FIGS. 4A and 4B are schematic perspective viewsof the liquid ejection head 3 of this use example. The liquid ejectionhead 3 is a line type liquid ejection head formed by linearly arranginga total of fifteen (15) recording element boards 10 (in line), each ofwhich is capable of ejecting four color inks of CMYK. As illustrated inFIG. 4A, the liquid ejection head 3 includes recording element boards10, flexible wiring boards 40, signal input terminals 91 and powersupply terminals 92, the signal input terminals 91 and the power supplyterminals 92 being electrically connected to the recording elementboards 10 and the flexible wiring boards 40 by way of an electricalwiring board 90. The signal input terminals 91 and the power supplyterminals 92 are electrically connected to the control unit (notillustrated) of recording apparatus 1000 and respectively supply logicsignals and electric power necessary for ejecting liquid to therecording element boards 10. Intensive wiring can be realized by theelectric circuits in the electrical wiring board 90 to reduce the numberof signal input terminals 91 and that of power supply terminals 92relative to the number of recording element boards 10. Then, as aresult, the number of electric connections that need to be removed andreestablished at the time of installing the liquid ejection head 3 andalso at the time of replacing the liquid ejection head 3 can beminimized. As illustrated in FIG. 4B, liquid connection sections 111located at the opposite edges of the liquid ejection head 3 areconnected to the liquid supply system of the recording apparatus 1000.With this arrangement, four color inks of CMYK are supplied from thesupply system of the recording apparatus 1000 to the liquid ejectionhead 3 and the inks that have passed through the inside of the liquidejection head 3 are collected and brought back to the supply system ofthe recording apparatus 1000. In this way, each of the four color inkscan circulate by way of the respective ink routes in the recordingapparatus 1000 and also the respective ink routes in the liquid ejectionhead 3.

FIG. 5 is an exploded schematic perspective view of the liquid ejectionhead 3 of Use Example 1, representing the components and the unitsthereof. In FIG. 5, liquid ejection unit 300, liquid supply units 220and electrical wiring board 90 are fitted to cabinet 80. The liquidsupply units 220 are provided with respective liquid connection sections111 (see FIGS. 2 and 3) and filters 221 (see FIGS. 2 and 3) forrespective color inks are arranged in the insides of the liquid supplyunits 220 and held in communication with corresponding openings at theliquid connection sections 111 in order to remove foreign objectscontained in the liquids being supplied through them. Each of the twoliquid supply units 220 is provided with two filters 221 for twodifferent colors. After passing through the respective filters 221, theliquids are then fed to the negative pressure control units 230 arrangedon the liquid supply units 220 so as to correspond to the respectivecolors. The negative pressure control units 230 are units havingpressure regulating valves for the four different colors that aredesigned to remarkably attenuate changes in the pressure losses in thesupply systems (the supply systems arranged at the upstream side of theliquid ejection head 3) of the recording apparatus 1000 that can takeplace due to fluctuations in the liquid flow rates by means of thevalves and the spring members arranged in the inside of the units. Dueto this arrangement, changes in the negative pressure at the downstreamside of each of the pressure control units (at the side of the liquidejection unit 300) can be confined within a certain range so as tostabilize the negative pressure. Each of the negative pressure controlunits 230 of the four colors contains two pressure regulating valves forits own color and different control pressures are respectively set inthe two pressure regulating valves as described above by referring toFIG. 2. Of the two pressure regulating valves, the high pressure sideone communicates with the common supply channel 211 in the liquidejection unit 300 by way of the liquid supply unit 220 and the low sideone communicates with the common collection channel 212 in the liquidejection unit 300 by way of the liquid supply unit 220.

The cabinet 80 includes a liquid ejection unit support 81 and anelectrical wiring board support 82. Thus, the cabinet 80 supports theliquid ejection unit 300 and the electrical wiring board 90 and securesthe rigidity of the liquid ejection head 3. The electrical wiring boardsupport 82 is a member for supporting the electrical wiring board 90,which member is rigidly held to the liquid ejection unit support 81 bymeans of screws. The liquid ejection unit support 81 takes the role ofcorrecting warps and deformations that may arise to the liquid ejectionunit 300 and secures the relative positional accuracy of the pluralityof recording element boards 10, thereby suppressing stripes andunevenness that may otherwise appear on the images recorded by therecording apparatus. Therefore, the liquid ejection unit support 81preferably represents a satisfactory level of rigidity. Materials thatcan preferably be used for the liquid ejection unit support 81 includemetallic materials such as SUS (stainless steel) and aluminum andceramic materials such as alumina. The liquid ejection unit support 81is provided with openings 83 and 84 for receiving rubber joints 100. Theliquid supplied from the liquid supply units 220 is guided to the thirdflow channel forming member 70 that the liquid ejection unit 300includes by way of the rubber joints 100.

The liquid ejection unit 300 includes a plurality of liquid ejectionmodules 200 and a flow channel forming member 210 and a cover member 130is fitted to the surface of the liquid ejection unit 300 that faces therecording medium. As illustrated in FIG. 5, the cover member 130 is amember having a surface that appears like a picture frame and anelongated oblong opening 131, through which the recording element boards10 and seal members 110 (see FIGS. 9A and 9B) that belong to therespective ejection modules 200 are exposed to the outside. The framesurrounding the opening 131 operates as contact surface that contactsthe cap member for covering the liquid ejection head 3 in a recordingstandby state. Therefore, an adhesive agent, a sealing material and afilling material are preferably applied to the liquid ejection unit 300along the periphery of the opening 131 to flatten the undulations andfill the gaps on the ejection surface of the liquid ejection unit 300 inorder to produce a closed space in the liquid ejection head 3 when theliquid ejection head is capped by the cover member 130.

Now, the configuration of the flow channel forming member 210 of theliquid ejection unit 300 will be described below. As illustrated in FIG.5, the flow channel forming member 210 is formed by sequentially layingfirst flow channel forming member 50, second flow channel forming member60 and third flow channel forming member 70 one on the other in theabove-mentioned order. The flow channel forming member 210 distributesthe liquid supplied from the liquid supply units 220 to the individualejection modules 200 and returns the liquid flowing back from theejection modules 200 to the liquid supply units 220. The flow channelforming member 210 is rigidly held to the liquid ejection unit support81 by means of screws to suppress warps and deformations that mayotherwise arise to the flow channel forming member 210.

FIGS. 6A through 6F are views representing the front surfaces and rearsurfaces of the first through third flow channel forming members. Morespecifically, FIG. 6A represents the surface of the first flow channelforming member 50 on which the ejection modules 200 are mounted and FIG.6F represents the surface of the third flow channel forming member 70that is held in contact with the liquid ejection unit support 81. Thefirst flow channel forming member 50 and the second flow channel formingmember 60 are joined together such that the contacting surfacesillustrated in FIGS. 6B and 6C are located vis-à-vis relative to eachother, whereas the second flow channel forming member and the third flowchannel forming member are joined together such that the contactingsurfaces illustrated in FIGS. 6D and 6E are located vis-à-vis relativeto each other. As the second flow channel forming member 60 and thethird flow channel forming member 70 are joined together, a total ofeight (8) common channels that extend in the longitudinal direction ofthe flow channel forming member are produced by the common channelforming grooves 62 formed on the second flow channel forming member 60and the common channel forming grooves 71 formed on the third flowchannel forming member 70. Then, as a result, a set of a common supplychannel 211 and a common collection channel 212 is formed for each ofthe four colors of CMYK in the inside of the flow channel forming member210 (see FIG. 7). Communication ports 72 of the third flow channelforming member 70 are held in communication with the respective holes ofthe rubber joints 100 so as to be fluidically connected to the liquidsupply units 220. A plurality of communication ports 61 is formed at thebottom surfaces of the common channel forming grooves 62 of the secondflow channel forming member 60 such that each of them communicates withone of the opposite edges of corresponding one of the individual channelforming grooves 52 of the first flow channel forming member 50. Acommunication port 51 is formed at the other edge of each of theindividual channel forming grooves 52 of the first flow channel formingmember 50 such that the individual channel forming grooves 52fluidically communicate with the plurality of ejection modules 200 byway of the communication ports 51. The individual channel forminggrooves 52 allow flow channels to be intensively arranged at and nearthe center of the flow channel forming member.

The first through third flow channel forming members 50, 60 and 70 arepreferably formed by using a material that has an anti-corrosionproperty relative to liquid and also a low linear expansion coefficient.A composite material produced by using, for example, alumina, LCP(liquid crystal polymer), PPS (poly-phenyl sulfide) or PSF (polysulfone)as base material and adding an inorganic filler material is preferablyemployed for the first through third flow channel forming members 50, 60and 70. Inorganic filler materials that can be used for this purposeinclude micro particles and fibers of silica. The flow channel formingmember 210 may be formed by sequentially laying the three flow channelforming members one on the other and bonding them by means of anadhesive agent or, when a composite material is selected for it, bybonding the flow channel forming members together by means of welding.

Now, the connection relationship of the flow channels in the flowchannel forming member 210 will be described below by referring to FIG.7. FIG. 7 is an enlarged schematic perspective see-through view,representing part of the flow channels in the flow channel formingmember 210 formed by bonding the first through third flow channelforming members as viewed from the surface of the first flow channelforming member 50 on which ejection modules 200 are to be mounted.Common supply channels 211 (211 a, 211 b, 211 c, 211 d) and commoncollection channels 212 (212 a, 212 b, 212 c, 212 d) that extend in thelongitudinal direction of the liquid ejection head 3 for the four colorsof CMYK are arranged on the flow channel forming member 210. A pluralityof individual supply channels 213 (213 a, 213 b, 213 c, 213 d) that areformed by individual channel forming grooves 52 is connectedrespectively to the common supply channels 211 of the four colors by wayof the communication ports 61. Similarly, a plurality of individualcollection channels 214 (214 a, 214 b, 214 c, 214 d) that are formed byindividual channel forming grooves 52 is connected respectively to thecommon collection channels 212 of the four colors by way of thecommunication ports 61. Due to such a channel arrangement, liquid can bemade to flow intensively to the recording element boards 10 arranged ata center part of the flow channel forming member from the common supplychannels 211 by way of the individual supply channels 213. Additionally,liquid can be collected from the recording element boards 10 to thecommon collection channels 212 by way of the individual collectionchannels 214.

FIG. 8 is a schematic cross sectional view taken along line 8-8 in FIG.7. As illustrated in FIG. 8, the individual collection channels 214 aand 214 c are respectively held in communication with the ejectionmodules 200 by way of the communication ports 51. While only theindividual collection channels 214 a and 214 c are illustrated in FIG.8, some other cross sectional view will represent that the individualsupply channels 213 and the ejection modules 200 are respectively heldin communication with each other as seen from FIG. 7. Flow channels areformed in the support member 30 and the recording element board 10 thatare contained in each of the ejection modules 200 in order to supplyliquid from the first flow channel forming member 50 to the recordingelements 15 (see FIG. 10B) arranged on the recording element board 10.Similarly, channels are formed in the support member 30 and therecording element board 10 that are contained in each of the ejectionmodules 200 in order to collect (flow back) part or all of the liquidsupplied to the recording elements 15 down to the first flow channelforming member 50. Note that, for each of the four colors, the commonsupply channel 211 is connected to the negative pressure control unit230 (high pressure side) by way of the liquid supply unit 220 and thecommon collection channel 212 is connected to the negative pressurecontrol unit 230 (low pressure side) by way of the liquid supply unit220. The negative pressure control unit 230 is designed to produce apressure difference between the common supply channel 211 and the commoncollection channel 212. Thus, in the liquid ejection head 3 of this useexample where flow channels are connected in a manner as illustrated inFIGS. 7 and 8, a flow of liquid that flows through the route formed bysequentially connecting the common supply channel 211, the individualsupply channels 213, the recording element board 10, the individualcollection channels 214 and the common collection channel 212 isestablished for each of the four colors.

(Explanation of the Ejection Modules)

FIG. 9A is a schematic perspective view of one of the ejection modules200 and FIG. 9B is an exploded perspective view of the ejection module200. To prepare an ejection module 200, firstly a recording elementboard 10 and a flexible wiring board 40 are bonded to a support member30 having liquid communication ports 31 that are formed in advance.Then, the terminals 16 on the recording element board 10 arerespectively electrically bonded to the terminals 41 on the flexiblewiring board 40 by wire bonding and subsequently the wire bondingsection (electrical connection section) is covered and sealed by a sealmember 110. The terminals 42 arranged at the side of the flexible wiringboard 40 that is opposite to the side thereof located vis-à-vis therecording element board 10 are electrically connected to correspondingone of the connection terminals 93 (see FIG. 5) of the electrical wiringboard 90. Support member 30 operates as member for supporting therecording element board 10 and also as flow channel forming member forcausing the recording element board 10 and the flow channel formingmember 210 to fluidically communicate with each other. Therefore, thesupport member 30 is preferably prepared so as to represent a highdegree of flatness and also to be capable of being highly reliablyjoined to the recording element board. Examples of preferable materialsthat can be used to form the support member 30 include alumina and resinmaterials.

(Explanation of the Structure of the Recording Element Boards)

Now, the configuration of the recording element boards 10 in this useexample will be described below. FIG. 10A is a schematic plan view ofthe surface of a recording element board 10 where ejection ports 13 areformed. FIG. 10B is an enlarged view of the part of the recordingelement board 10 that is surrounded by a circle and indicated by 10B inFIG. 10A. FIG. 10C is a plan view of the surface of the recordingelement board 10 that is opposite to the surface illustrated in FIG.10A. As illustrated in FIGS. 10A and 10B, ejection ports are formed infour rows so as to correspond to inks of four colors on ejection portforming member 12 of the recording element board 10. In the followingdescription, the direction in which the rows of ejection ports, eachhaving a plurality of ejection ports 13, extend will be referred to as“ejection port row direction”.

As illustrated in FIG. 10B, recording elements 15 are also arranged onthe recording element board 10 at positions that correspond to therespective ejection port 13. The recording elements 15 are heatgenerating elements that generate heat necessary to cause liquid tobubble by thermal energy. For the purpose of the present invention,however, the recording elements 15 may not necessarily be heatgenerating elements. In other words, the recording elements according tothe present invention may be selected from various elements that cangenerate energy to be utilized to eject liquid such as piezoelectricelements. Pressure chambers 23 that contain respective recordingelements 15 in the insides thereof are produced by partition walls 22.The recording elements 15 are electrically connected to the terminals 16illustrated in FIG. 10A by way of electrical wiring (not illustrated)arranged on the recording element board 10. The recording elements 15generate heat to boil the liquid in them according to the pulse signalsinput to them from the control circuit of the recording apparatus 1000by way of the electrical wiring board 90 (see FIG. 5) and the flexiblewiring board 40 (see FIG. 9B) and eject liquid from their ejection ports13 under the force of the bubbles produced as a result of the boiling.As illustrated in FIG. 10B, a liquid supply channel 18 extends along oneof the opposite sides of each of the rows of ejection ports and a liquidcollection channel 19 extends along the other side of the row ofejection ports. The liquid supply channels 18 and the liquid collectionchannels 19 are channels arranged on the recording element board 10 andextend in the extending direction of the rows of ejection ports and eachof them is held in communication with the related ones of the ejectionports 13 respectively by way of related ones of either supply ports 17 aor collection ports 17 b. The supply ports 17 a are employed to supplyliquid to the pressure chambers 23, whereas the collection ports 17 bare employed to collect liquid from the pressure chambers 23. The liquidin the pressure chambers 23 is forced to circulate to and from theoutside by way of the respective supply ports 17 a and the respectivecollection ports 17 b thereof.

As illustrated in FIG. 10C and also in FIG. 11, which will be describedhereinafter, a sheet-like lid member 20 is laid on the back surfaces ofthe recording element boards 10 that are opposite to the surfacesthereof where ejection ports 13 are formed. The lid member 20 isprovided with a plurality of openings 21 that communicate with theliquid supply channels 18 and the liquid collection channels 19 as willbe described in greater detail hereinafter. In the instance of this useexample, three openings 21 are provided on the lid member 20 for each ofthe liquid supply channels 18 while two openings 21 are provided on thelid member 20 for each of the liquid collection channels 19. Each of theopenings 21 of the lid member 20 illustrated in FIG. 10B is held incommunication with a plurality of communication ports 51 illustrated inFIG. 6A. As illustrated in FIG. 11, the lid member 20 also operates asparts of the walls of the liquid supply channels 18 and also parts ofthe walls of the liquid collection channels 19 that are formed in thesubstrate 11 of the recording element board 10. The lid member 20 ispreferably satisfactorily anti-corrosive relative to liquid and requiredto represent a high degree of accuracy in terms of shape and positionsof the openings 21 from the viewpoint of prevention of undesired mixingof liquids of different colors. For this reason, the lid member 20 ispreferably made of a photosensitive resin material or made from asilicon plate and the openings 21 are produced by way of aphotolithography process. As seen from the above description, the lidmember 20 changes the pitch of the flow channels by means of theopenings 21 thereof and hence it desirably has a small thickness fromthe viewpoint of pressure loss. Therefore, the lid member 20 ispreferably formed as a filmy member.

Now, how liquid flows in each of the recording element boards 10 will bedescribed below. FIG. 11 is a schematic perspective view of a recordingelement board 10 and a lid member illustrated in cross section as takenalong line 11-11 in FIG. 10A. The recording element board 10 is formedby laying an ejection port forming member 12 that is made of aphotosensitive resin material on a substrate 11 that is made of Si. Thelid member 20 is bonded to the back surface of the substrate 11.Recording elements 15 are formed on the front surface of the substrate11 (see FIG. 10B) and grooves for forming liquid supply channels 18 andliquid collection channels 19, which extend along the rows of ejectionports, are formed on the opposite surface, or the back surface, thereof.The liquid supply channels 18 and the liquid collection channels 19,which are formed by the substrate 11 and the lid member 20, arerespectively connected to the common supply channels 211 and the commoncollection channels 212 in the flow channel forming member 210 and apressure difference is produced between the liquid supply channels 18and the liquid collection channels 19. While the liquid ejection head 3is driven to operate for recording by ejecting liquid from some of theejection ports 13 thereof, liquid flows at the ejection ports that arenot ejecting liquid. Some of the liquid in the liquid supply channel 18of each of the rows of ejection ports flows to the corresponding liquidcollection channel 19 by way of the supply ports 17 a, the pressurechambers 23 and the collection ports 17 b. Thus, the liquid, or the ink,in the ejection ports 13 that are not ejecting liquid and also in therelated pressure chambers 23 whose viscosity is raised by evaporation,and bubbles and the foreign objects contained in the liquid can becollected to the liquid collection channels 19 by the flow (indicated byarrows C in FIG. 11). The liquid flow can also suppress the increase inthe viscosity of the liquid, or the ink, held in those ejection ports 19and those pressure chambers 23. The liquid collected to the liquidcollection channels 19 is then collected by way of the openings 21 ofthe lid member 20 and the liquid communication ports 31 of the supportmembers 30 (see FIG. 9B) sequentially to the communication ports 51 inthe flow channel forming members 210, the individual collection channels214 and the common collection channels 212. Then, ultimately the liquidis collected to the supply route of the recording apparatus 1000.

Differently stated, the liquid supplied from the recording apparatus1000 main body to the liquid ejection head 3 flows so as to supply andto be collected in a manner as described below. The liquid firstly flowsfrom the liquid connection sections 111 of the liquid supply units 220into the inside of the liquid ejection head 3. Then, the liquid issequentially fed to the rubber joints 100, the communication ports 72and the common channel forming grooves 71 formed in the third flowchannel forming member, the common channel forming grooves 62 and thecommunication ports 61 formed in the second flow channel forming member22 and the individual channel forming grooves 52 and the communicationports 51 formed in the first flow channel forming member. Thereafter,the liquid is supplied to the pressure chambers 23 sequentially by wayof the liquid communication ports 31 formed in the support members 30,the openings 21 formed in the lid members and the liquid supply channels18 and the supply ports 17 a formed in the substrate 11. Of the liquidsupplied to the pressure chambers 23, the part that is not ejected fromejection ports 13 flows sequentially through the collection ports 17 band the liquid collection channels 19 formed in the substrate 11, theopenings 21 formed in the lid members and the liquid communication ports31 formed in the support members 30. Furthermore, the part of the liquidsequentially flows through the communication ports 51 and the individualchannel forming grooves 52 formed in the first flow channel formingmember, the communication ports 61 and the common channel forminggrooves 62 formed in the second flow channel forming member, the commonchannel forming grooves 71 and the communication ports 72 formed in thethird flow channel forming member 70 and the rubber joints 100.Thereafter, the part of the liquid flows out from the liquid connectionsections 111 arranged in the liquid supply units to the outside of theliquid ejection head 3. In the instance of the first circulation routeillustrated in FIG. 2, the liquid that flows into it from the liquidconnection sections 111 is fed to the rubber joints 100 after passingthrough the negative pressure control unit 230. In the instance of thesecond circulation route illustrated in FIG. 3, the liquid collectedfrom pressure chambers 23 flows out to the outside of the liquidejection head from the liquid connection sections 111 by way of thenegative pressure control units 230 after passing through the rubberjoints 100.

Additionally, as illustrated in FIGS. 2 and 3, all the liquid that flowsin from one of the opposite edges of the communication supply channel211 of the liquid ejection unit 300 is not necessarily supplied to thepressure chambers 23 by way of the individual supply channels 213. Inother words, part of the liquid may flow into the liquid supply unit 220by way of the other edge of the communication supply channel 211 withoutflowing into the individual supply channels 213. As a result ofproviding flow channels through which liquid flows without passingthrough any recording element board 10, any back flow of the circulatingliquid can be suppressed even though the recording element boards 10 aremade to possess fine channels that represent a large resistance againstflowing liquid as in the case of this use example. Thus, the liquidejection head 3 of this use example can suppress the phenomenon ofuneven ejections and non-ejections and hence can record high qualityimages because any increase of liquid viscosity can be suppressed at andnear the ejection ports 13 and the pressure chambers 23.

(Explanation of the Positional Relationship Among the Recording ElementBoards)

FIG. 12 is an enlarged schematic plan view of a neighboring area of therecording element boards 10 of two adjacently located ejection modulesof Use Example 1 of the present invention. Substantiallyparallelogrammic recording element boards 10 as illustrated in FIGS. 10Athrough 10C are employed in this use example. As illustrated in FIG. 12,the rows of ejection ports 14 a through 14 d of each of the recordingelement boards 10 are arranged such that they are inclined by a certainangle relative to the direction in which recording mediums are conveyed.As a result of this arrangement, at least one of the ejection ports ofeach row of ejection ports 13 of a recording element board 10 overlapsone of the ejection ports of the adjacently arranged recording elementboard 10 in a neighboring area of them as viewed in the direction inwhich recording mediums are conveyed. In FIG. 12, two ejection portsoverlap each other on each of the lines D. With this arrangement, evenwhen one of the recording element boards 10 is displaced from its properposition to some extent, the overlapping ejection ports can be driven tooperate in a controlled manner and compensate the displacement so as tomake black strips and a blank area shining phenomenon, if any, minimallynoticeable. The plurality of recording element boards 10 may be arrangednot in a zigzag manner but linearly (inline). Even with the latterarrangement, due to the effect as described above by referring to FIG.12, black strips and a blank area shining phenomenon can be minimized inrecording element board connecting areas, while suppressing any increaseof the length of the liquid ejection head 3 as viewed in the recordingmedium conveying direction. While the recording element boards 10 ofthis use example are parallelogrammic in plan view, the presentinvention is by no means limited to the use of paralleogrammic recordingelement boards and the principle of the present invention isadvantageously applicable to instances where, for example, recordingelement boards 10 that are rectangular, trapezoidal or of some othershape are employed for a liquid ejection head according to the presentinvention.

(Use Example 2)

Now, the configuration of the recording apparatus 1000 and that of theliquid ejection head 3 of Use Example 2 of the present invention will bedescribed below. Note that Use Example 2 will be described below mainlyin terms of differences between Use Example 1 and this example and theexplanation of the parts of the configurations of this example that aresimilar to those of the configurations of Use Example 1 may be omitted.

(Explanation of the Inkjet Recording Apparatus)

FIG. 20 is a schematic perspective view of the inkjet recordingapparatus of Use Example 2 of the present invention, schematicallyrepresenting the configuration thereof. The recording apparatus 1000 ofUse Example 2 differs from that of Use Example 1 in that a total of four(4) liquid ejection heads 3, which are designed for monochromaticrecording so as to correspond to inks of CMYK, are arranged side by sidefor the purpose of full color recording operations using recordingmediums 2. While only a single row of ejection ports is available foreach color in Use Example 1, a total of twenty (20) rows of ejectionports are available for each color in Use Example 2 (FIG. 19A). Thisarrangement allows very high speed recording operations to be executedas the recording data input to the recording apparatus can appropriatelybe allocated to the plurality of rows of ejection ports. Additionally,if there are ejection ports that have become no longer capable ofejecting liquid in some of the rows of ejection ports, the ejectionports of other rows that are located at corresponding positions relativeto the former ejection ports as viewed in the recording medium conveyingdirection are driven to complementarily eject liquid to secure thereliability of the recording apparatus 1000. Therefore, this recordingapparatus 1000 can suitably be used for commercial printing purposes. Asin Use Example 1, the supply systems of the recording apparatus 1000,the buffer tanks 1003 and the main tanks 1006 (see FIG. 2) arefluidically connected to the respective liquid ejection heads 3 in thisuse example. Electrical control units for transmitting electric powerand ejection control signals to the liquid ejection heads 3 areelectrically connected to the respective liquid ejection heads 3.

(Explanation of the Circulation Routes)

Either the first circulation route illustrated in FIG. 2 or the secondcirculation route illustrated in FIG. 3 may be used for the liquidcirculation route between the recording apparatus 1000 and the liquidejection heads 3 of this use example as in Use Example 1.

(Explanation of the Configuration of the Liquid Ejection Heads)

Now, the configuration of the liquid ejection heads 3, which are samewith each other, of Use Example 2 of the present invention will bedescribed below. FIGS. 13A and 13B are schematic perspective views ofone the liquid ejection heads of Use Example 2 of the present invention,schematically representing the configuration thereof. The liquidejection head 3 includes a total of sixteen (16) recording elementboards 10 linearly arranged side by side in the longitudinal directionof the liquid ejection heed 3. The liquid ejection head 3 is a line typeinkjet recording head that can be driven for monochromatic recordingusing ink of a single color. As in Use Example 1, the liquid ejectionhead 3 includes liquid connection sections 111, signal input terminals91 and power supply terminals 92. Since the liquid ejection head 3 ofthis use example has a large number of rows of ejection ports ifcompared with Use Example 1, signal input terminals 91 and power supplyterminals 92 are arranged along the opposite edges of the liquidejection head 3. This is to reduce voltage falls and signal transmissiondelays that can take place in the wiring sections arranged on therecording element boards 10.

FIG. 14 is an exploded schematic perspective view of the liquid ejectionhead of Use Example 2 of the present invention. The parts and the unitsof the liquid ejection head 3 are individually illustrated in FIG. 14 toillustrate their respective functions. The role of each of the units andthe members and the sequence of arrangement of the units and the membersfrom the viewpoint of liquid flow are basically the same as those of UseExample 1 but the functions thereof for securing the rigidity of theliquid ejection head differs from those of Use Example 1. In Use Example1, the rigidity of the liquid ejection head is secured mainly by theliquid ejection unit support 81. In Use Example 2, on the other hand,the rigidity of the liquid ejection head is secured by the second flowchannel forming member 60 included in the liquid ejection unit 300. Theliquid ejection unit supports 81 of this use example are respectivelyconnected to the opposite edges of the second flow channel formingmember 60 and the liquid ejection unit 300 is mechanically bonded to thecarriage of the recording apparatus 1000 to properly place the liquidejection head 3 in position. Liquid ejection units 220 that includerespective negative pressure control units 230 and electrical wiringboard 90 are bonded to the liquid ejection unit supports 81. Filters(not illustrated) are contained respectively in the two liquid supplyunits 220. The two negative pressure control units 230 are so designedas to control pressure by means of their respective negative pressuresthat differ from each other and one of which is higher than the other.Additionally, when the high pressure side negative pressure control unit230 and the low pressure side negative pressure control unit 230 arearranged at the opposite edges of the liquid ejection head 3 asillustrated in FIG. 14, the liquid in the common supply channels 211 andthe liquid in the common collection channels 212 extending in thelongitudinal direction of the liquid ejection head 3 flow in mutuallyopposite directions. With this arrangement, heat exchanges between thecommon supply channels 211 and the common collection channels 212 arefacilitated to reduce the temperature difference between the two sets ofcommon channels. For this reason, temperature differences can scarcelyoccur among the plurality of recording element boards 10 arranged alongthe common channels to provide an advantage that uneven recordingsattributable to temperature differences can hardly take place.

Now, the flow channel forming member 210 of the liquid ejection unit 300will be described below in detail. As illustrated in FIG. 14, the flowchannel forming member 210 is formed by laying second flow channelforming member 60 on first flow channel forming member 50 and operatesto distribute the liquid fed from the liquid supply units 220 toejection modules 200. The flow channel forming member 210 also operatesas flow channel forming member for returning the liquid flowing backfrom the ejection modules 200 to the liquid supply units 220. The secondflow channel forming member 60 of the flow channel forming member 210 isa member in which common supply channels 211 and common collectionchannels 212 are formed and, at the same time, takes a role of mainlysecuring the rigidity of the liquid ejection head 3. For this reason,the second flow channel forming member 60 is preferably formed by usinga material that is satisfactorily anti-corrosive relative to liquid andhas a high degree of mechanical strength. More specifically, materialsthat can suitably be used for the second flow channel forming member 60include SUS, Ti and alumina.

FIG. 15A represents the surface of the first flow channel forming member50 on which the ejection modules 200 are to be mounted and FIG. 15Brepresents the opposite side surface thereof that is to be brought intocontact with the second flow channel forming member 60. Unlike UseExample 1, the first flow channel forming member 50 of Use Example 2 isformed by arranging a plurality of component members side by side tocorrespond to the ejection modules 200. When the first flow channelforming member 50 is formed by using a plurality of component members asdescribed above, the length of the first flow channel forming member 50can be made to correspond to that of the liquid ejection head.Therefore, the arrangement of this first flow channel forming member 50is particularly suitable for a relatively large scale liquid ejectionhead 3 that can accommodate itself to B2 size and larger recordingmediums. As illustrated in FIG. 15A, the communication ports 51 of thefirst flow channel forming member 50 fluidically communicate with theejection modules 200 and, as illustrated in FIG. 15B, the individualcommunication ports 53 of the first flow channel forming member 50fluidically communicate with the communication ports 61 of the secondflow channel forming member 60. FIG. 15C represents the surface of thesecond flow channel forming member 60 that is to be brought into contactwith the first flow channel forming member 50 and FIG. 15D represents across section of a central part of the second flow channel formingmember 60 as viewed in the thickness direction thereof, while FIG. 15Erepresents the surface of the second flow channel forming member 60 thatis to be brought into contact with the liquid supply units 220. Thefunctions of the flow channels and the communication ports of the secondflow channel forming member 60 are similar to those of the flow channelsand the communication ports of Use Example 1 for a single color. One ofthe pair of common channel forming grooves 71 of the second flow channelforming member 60 is a common supply channel 211 and the other is acommon collection channel 212 illustrated in FIG. 16. Each of them runsin the longitudinal direction of the liquid ejection head 3 such thatliquid is fed from one of the opposite edges to the other edge. UnlikeUse Example 1, the flow direction of the common supply channel 211 andthat of the common collection channel 212 are opposite relative to eachother in this use example.

FIG. 16 is a schematic perspective see-through view of a recordingembodiment board 10 and the flow channel forming member 210 of this useexample, representing the connection relationship thereof from theviewpoint of liquid flowing there. As illustrated in FIG. 16, a commonsupply channel 211 and a common collection channel 212 are arranged inthe flow channel forming member 210 so as to extend in the longitudinaldirection of the liquid ejection head 3. The communication ports 61 ofthe second flow channel forming member 60 are aligned with and connectedto the respective individual communication ports 53 of the first flowchannel forming member 50 to establish liquid supply routes from thecommunication ports 72 of the second flow channel forming member 60 tothe communication ports 51 of the first flow channel forming member 50by way of the common supply channel 211. Similarly, liquid supply routesare established from the communication ports 72 of the second flowchannel forming member 60 to the communication ports 51 of the firstflow channel forming member 50 by way of the common collection channel212.

FIG. 17 is a schematic cross sectional view taken along line 17-17 inFIG. 16. As illustrated in FIG. 17, common supply channel is linked tothe ejection modules 200 by way of an individual communication port 53and a communication port 51. While not-illustrated in FIG. 17, it willbe clear by seeing FIG. 16 that individual collection channels arelinked to the ejection modules 200 by way of similar routes as will berepresented in some other cross section. As in Use Example 1, theejection modules 200 and the recording element boards 10 are providedwith flow channels that communicate with the respective ejection ports13 such that part or all of the supplied liquid can flow back, passingthrough the ejection ports 13 (the pressure chambers 23) whose liquidejecting operations are suspended. Additionally, as in Use Example 1,the common supply channels 211 are connected to the negative pressurecontrol unit 230 (high pressure side) by way of related one of theliquid supply units 220, while the common collection channels 212 areconnected to the negative pressure control unit 230 (low pressure side)by way of the other liquid supply unit 220. Due to this arrangement thatgives rise to a pressure difference between the common supply channels211 and the common collection channels 212, a liquid flow takes placefrom the common supply channels 211 to the common collection channels212 by way of the ejection ports 13 (pressure chambers 23) of therecording element boards 10.

(Explanation of the Ejection Modules)

FIG. 18A is a schematic perspective view of an ejection module 200 andFIG. 18B is an exploded perspective view of the ejection module. Thedifference between an ejection module in Use Example 1 and this ejectionmodule lies in that a plurality of terminals 16 are arranged along theopposite edges running in the direction of the plurality of rows ofejection ports of the recording element board 10 (each long side portionof the recording element board 10) and that a pair of flexible wiringboards 40 that are electrically connected to these terminals 16 areprovided for a single recording element board 10. This arrangement isintroduced here because a total of twenty (20) rows of ejection portsare arranged in the recording element board 10, representing asignificant increase of rows of ejection ports from the eight (8) rowsof ejection ports in Use Example 1. In other words, this arrangement isintroduced in order to reduce the maximum distance from the terminals 16to the recording elements 15 that are arranged to correspond to the rowsof ejection ports, thereby reducing voltage falls and signaltransmission delays that may occur at the wiring section of therecording element board 10. Additionally, the liquid communication ports31 of the support member 30 are arranged in the recording element board10 so as to extend across all the rows of ejection ports. Otherwise, theejection modules are similar to those of Use Example 1.

(Explanation of the configuration of the recording element boards)

FIG. 19A is a schematic view of the surface of one of the recordingelement boards 10 where ejection ports 13 are arranged. FIG. 19C is aschematic view of the surface (rear surface) opposite to the oneillustrated in FIG. 19A. FIG. 19B is a schematic view of the surface(rear surface) of the recording element board 10 same as that of FIG.19C from which the lid member 20 is removed. As illustrated in FIG. 19B,liquid supply channels 18 and liquid collection channels 19 arealternately arranged on the rear surface of the recording element board10 so as to extend in the direction of the rows of ejection ports. Whilea significantly large number of rows of ejection ports are arranged ifcompared with Use Example 1, the intrinsic difference between UseExample 1 and this use example lies in that terminals 16 are arrangedalong the opposite edges of the recording element board 10 that run inthe direction of the rows of ejection ports as described above. Thebasic configuration of this use example including that each of the rowsof ejection ports is provided with a pair of a liquid supply channel 18and a liquid collection channel 19 and that the lid member 20 isprovided with openings 21 that communicate with the liquid communicationports 31 of the support member 30 is similar to that of Use Example 1.

Now, embodiments of the present invention will be described below interms of characteristic aspects thereof.

(First Embodiment)

FIGS. 21A and 21B are schematic perspective views of the liquid ejectionhead of the first embodiment of the present invention, schematicallyillustrating the configuration thereof. More specifically, FIG. 21A is aschematic perspective view of the liquid ejection head for ejectionliquid such as ink and FIG. 21B is an exploded schematic perspectiveview of the liquid ejection head.

The liquid ejection head 13 illustrated in FIGS. 21A and 21B includes aplurality of recording element boards 10, a plurality of support members30 and a flow channel forming member 210. The number of the recordingelement boards 10 is the same as the number of the support members 30.The recording element boards 10 are supported by the respective supportmembers 30 and the plurality of support members 30 are arranged side byside on the single flow channel forming member 210. FIGS. 22A through22D are schematic top views of the liquid ejection head 3, representingfour different exemplar shapes and four different exemplar arrangementsthat can be used for the recording element boards 10 of the liquidejection head 3 of this embodiment. In the instance of FIG. 22A,recording element boards 10 having a parallelogrammic profile arearranged in a row. The expression of a “parallelogrammic profile” asused in the description of this example refers to a quadrangle each ofwhose angles formed by adjacent sides thereof is not orthogonal. In thefollowing description, the direction in which the recording elementboards 10 are arranged to form a row in the liquid ejection head 3 willbe referred to as longitudinal direction 401 and the directionperpendicular to the longitudinal direction 401 in a plane parallel tothe surfaces of the recording element boards 10 will be referred to asscanning direction 402.

In the instance of FIG. 22B, recording element boards 10, each having ashape where the sides of one of the pairs of oppositely disposed sidesrun in parallel with each other whereas the sides of the other pair areformed by step-like bent lines, are arranged to form a row. In theinstance of FIG. 22C, while recording element boards 10 having aparallelogrammic profile are arranged in a row as in FIG. 22A, any twoadjacently located recording element boards 10 are displaced from eachother in the scanning direction 402. In the instance of FIG. 22D,rectangular recording element boards 10 are arranged in a row.

In each of the instances of FIGS. 22A through 22C, any two adjacentlylocated recording element boards 10 at least partly overlap each otherboth in the longitudinal direction and in the scanning direction. In theinstance of FIG. 22D, any two adjacently located recording elementboards 10 overlap each other only in the longitudinal direction.

FIGS. 23A and 23B are schematic illustrations of positional displacementof rows of ejection ports of liquid ejection head 3. FIG. 23A is anenlarged schematic view of two adjacently located recording elementboards 10 having a profile same as that of recording element boards 10illustrated in FIG. 22A, representing the width of displacement 403 ofthe corresponding rows of ejection ports. As illustrated in FIG. 23A,displacement of rows of ejection ports appear in neighboring areas ofthe recording element boards 10 and the smaller the inter-elementdistance 404, which is the distance between the adjacently locatedrecording element boards 10, the smaller the width of displacement 403of rows of ejection ports. In other words, a smaller inter-elementdistance 404 is so much better for reducing width of displacement 403 ofrows of ejection ports. The above description is applicable not only tothe instance of FIG. 22A but also generally to liquid ejection heads 3where adjacently located recording element boards 10 at least partlyoverlap each other both in the longitudinal direction and in thescanning direction as in the instances of FIGS. 22B and 22C.

FIG. 23B is an enlarged schematic view of a neighboring area of twoadjacently located recording element boards 10 in the instance of FIG.22D. While no positional displacement takes place among rows of ejectionports in the instance of FIG. 23B, a smaller inter-element distance 404is so much better as in the case of the liquid ejection head to whichFIG. 22A is applicable. This is because the smaller the inter-elementdistance 404, the smaller the gap 405 between adjacently located rows ofejection ports in a neighboring area. While a liquid ejection head 3where adjacently located recording element boards 10 at least partlyoverlap each other both in the longitudinal direction and in thescanning direction as illustrated in FIG. 22A will be described below,the instance of FIG. 23B can also provide advantages similar to thethose of the liquid ejection head of FIG. 22A.

Now, the characteristics of this embodiment will be described in greaterdetail below.

FIG. 24 is a schematic cross-sectional lateral view of a neighboringarea of two adjacently located recording element boards 10 of the firstembodiment. As illustrated in FIG. 24, in the gap area 410 between thetwo adjacently located recording element boards 10, the contactingsurfaces 411 of the recording element boards 10 and the support members30 are separated away from the oppositely disposed edges 412 of therecording element boards 10. In other words, the oppositely disposededges 412 of the recording element boards 10 project outwardly from thecorresponding edges 413 of the support members 30 to make the distance(gap) between the adjacently located recording element boards 10 smallerthan the distance (gap) between the adjacently located support members30.

Each of the recording element boards 10 has a circuit and othercomponents prepared in advance in a wafer process (semiconductorprocess) and is typically formed by using silicon. Any of variousetching and dicing techniques are typically employed to produce thecircumferential profile of the recording element boards 10. On the otherhand, the support members 30 are prepared by machining and/or molding.Resin or metal such as SUS is typically used to produce support members30. Thus, the processing accuracy of the recording element boards 10 ishigher than the processing accuracy of the support members 30.

Referring to FIG. 24, if the edges of the recording element boards 10 donot project outwardly from the edges of the support members 30, theaccuracy of the inter-element distance 404, which is the distancebetween the two adjacently located recording element boards 10 isdetermined by the processing accuracy of the support members 30 and themounting position alignment accuracy of the recording element boards 10.This is because the support members 30 can interfere with each other ifan attempt is made to reduce the inter-element distance 404 so as to besmaller than the distance that is nominally limited by the processingaccuracy of the support members 30 and the mounting position alignmentaccuracy of the recording element boards 10.

To the contrary, when the edges 412 of the recording element boards 10project outwardly from the edges of the support members 30 as in thisembodiment, the accuracy of the inter-element distance 404 between theadjacently located recording element boards 10 is not limited by theprocessing accuracy of the support members 30. The accuracy of theinter-element distance 404 is determined by the processing accuracy ofthe recording element boards 10 and the mounting position alignmentaccuracy of the recording element boards 10. With this arrangement, ifthe processing accuracy of the support members 30 and the mountingposition alignment accuracy of the recording element boards 10 arerelatively low, the support members 30 would not interfere with eachother so long as the edges of the recording element boards 10 projectoutwardly from the edges of the support members 30 by a distance greaterthan the dimensional tolerance of the support members 30. Thus, thedistance between the two adjacently located recording element boards 10can be reduced by configuring the liquid ejection head 3 in a manner aswill be described below.

FIGS. 25A, 25B, 25C and 25D are schematic illustrations of some of theadvantages of the liquid ejection head of this embodiment and representside views of neighboring areas of adjacently located recording elementboards 10 of the liquid ejection head. More specifically, FIG. 25Arepresents a first comparative example and FIG. 25B represents a firstexample of this embodiment, while FIG. 25C represents a secondcomparative example and FIG. 25D represents a second example of thisembodiment. FIGS. 25A and 25B represent instances where support members30 carrying respective recording element boards 10 mounted thereon arearranged on a flow channel forming member 210 and FIGS. 25C and 25Drepresent instance where recording element boards 10 are mounted onrespective support members 30 arranged on a flow channel forming member210.

Assume here that the processing accuracy of the support members 30 is±0.1 mm and the processing accuracy of the recording element boards 10is ±0.01 mm, while the mounting alignment accuracy of the supportmembers 30 is ±0.1 mm and the mounting alignment accuracy for therecording element boards 10 is ±0.01 mm.

In the comparative example illustrated in FIGS. 25A and 25C, the edgesof the recording element boards 10 do not project outwardly from theedges of the support members 30. In these instances, a value greaterthan 0.4 mm obtained by adding the processing accuracy of each of thesupport members 30 to the mounting alignment accuracy of each of thesupport members 30 and doubling the sum needs to be selected for theinter-member distance 406, which is the distance between the twoadjacently located support members 30. In other words, the inter-elementdistance 404 is at least equal to 0.4 mm.

As for the first example of the this embodiment illustrated in FIG. 25B,the inter-element distance 404 may be made to be equal to 0.04 mmobtained by adding the processing accuracy of each of the recordingelement boards 10 to the mounting alignment accuracy of each of therecording element boards 10 and doubling the sum. Therefore, theinter-element distance 404 of the first example of this embodiment canbe reduced by 0.36 mm from the inter-element distance 404 of thecomparative example illustrated in FIG. 25A.

As for the second example of this embodiment illustrated in FIG. 25D,the inter-element distance 404 may be made to be equal to be 0.22 mmobtained by adding the processing accuracy of each of the recordingelement boards 10 to the mounting alignment accuracy of each of thesupport members 30 and doubling the sum. Therefore, the inter-elementdistance 404 of the second example of this embodiment can be reduced by0.18 mm from the inter-element distance 404 of the comparative exampleillustrated in FIG. 25C.

In the instance of FIG. 25D, if the mounting alignment accuracy of therecording element boards 10 is low to a certain extent, theinter-element distance 404 can further be reduced by raising themounting alignment accuracy of the support members 30. For example, theinter-element distance 404 can be made to be equal to 0.04 mm by makingthe mounting alignment accuracy of each of the recording element boards10 to be equal to 0.1 mm and making the mounting alignment accuracy ofeach of the support members 30 to be equal to 0.01 mm. In this example,the member mounting step that requires a high degree of accuracy needsto be executed only once.

As described above, the inter-element distance 404 can be reduced bymaking the edges 412 of the recording element boards 10 projectoutwardly relative to the edges 413 of the support members 30 to by turnreduce the displacement width 403 of the rows of ejection ports inneighboring areas of adjacently located recording element boards 10.Therefore, the displacement width in neighboring areas of adjacentlylocated recording element boards 10 in the direction of scanningrecording mediums 2 can be reduced to by turn reduce the displacementwidth 403 of rows of ejection ports without being subjected tolimitations imposed by the processing accuracy of support members 30 andthe mounting alignment accuracy of the support members 30. Then, as aresult, problems such as unevenness of images at positions thereofcorresponding to neighboring areas of recording element boards 10 can beminimized and high quality images can be produced.

Additionally, with this embodiment, the problem that the adhesive agentemployed to bond the recording element boards 10 and the support members30 creeps up from the gaps 410 separating adjacently located recordingelement boards 10 to the first surfaces of the recording element boards10 where ejection ports 13 are arranged can be suppressed. Thus, when anadhesive agent is employed to bond the recording element boards 10 andthe support members 30, the arrangement of this embodiment where theedges of the recording element boards 10 are made to project outwardlyfrom the edges of the corresponding support members 30 provides theadvantage as described below. Namely, if the adhesive agent comes outfrom the bonded surfaces, the adhesive agent that comes out is forced toremain on the rear surfaces of the edge portions of the recordingelement boards 10 that project from the respective support members 30 toconsequently suppress the problem of the adhesive agent creeping up fromthe gaps 410.

Desirably, a plurality of support members 30 are arranged on a singleflow channel forming member 210. Then, support members 30 can accuratelybe arranged in the longitudinal direction 401 to make it possible toproduce high quality images.

The length of the part of the flow channel forming member 210 whererecording element boards 10 are arranged side by side is preferably notsmaller than the maximum width of recording mediums 2 that can be set inposition in the recording apparatus 1000. Such an arrangement allowsimprovement in the quality of the image to be recorded in areas thereofthat correspond to the neighboring areas of adjacently located recordingelement boards 10 and the high quality image can be recorded across theentire width of a recording medium 2.

While the recording element boards 10 are individually replaceable inthis embodiment, the present invention is not limited to such anarrangement. For example, a liquid ejection head 3 of which therecording element boards 10 are not individually replaceable but thesupport members 10 can advantageously be individually processed can alsoprovide advantages similar to those of this embodiment.

Thus, the requirement to be satisfied by the configuration of thisembodiment is only that the edges of adjacently located recordingelement boards 10 project outwardly from the edges of correspondingsupport members 30. As illustrated in FIGS. 22A through 22D, the supportmembers 30 can be made to stably support the recording element boards 10by making the edges of support members 30 project outwardly from theedges of the corresponding recording element boards 10 at the sideswhere no adjacently located recording element boards 10 are found.Additionally, each of the support members 30 can also be made to stablysupport the flexible wiring board 40 bonded to the recording elementboard 10 as illustrated in FIGS. 9A and 9B. As described above indetail, recording element boards 10 are preferably made to projectoutwardly relative to corresponding support members 30 at the sideswhere the recording element boards 10 are arranged side by side. On theother hand, support members 30 are preferably made to project outwardlyfrom corresponding recording element boards 10 at the sides where noadjacently located recording element boards 10 are arranged (at thesides where support members are bonded to respective flexible wiringboards 40).

In the following description, one of any two adjacently locatedrecording element boards 10 will be referred to as the first recordingelement board and the other will be referred to as the second recordingelement board. Similarly, the support member 30 supporting the firstrecording element board will be referred to as the first support memberand the support member 30 supporting the second recording element boardwill be referred to as the second support member. Then, the first andsecond support members are arranged side by side on the flow channelforming member 210. Additionally, the edge of the first recordingelement board located close to the second recording element boardpreferably projects toward the second recording element board from theedge of the first support member located close to the second supportmember. Similarly, the edge of the second recording element boardlocated close to the first recording element board preferably projectstoward the first recording element board from the edge of the secondsupport member located close to the first support member.

However, the present invention is by no means limited to the modes ofarrangement illustrated in FIGS. 22A through 22D and the presentinvention is also applicable to an arrangement where each of therecording element boards 10 projects outwardly from the correspondingsupport member 30 along all the circumference thereof.

(Second Embodiment)

FIGS. 26A and 26B and FIGS. 27A and 27B schematically illustrate thesecond embodiment of liquid ejection head according to the presentinvention. FIGS. 26A and 26B are schematic illustrations of the liquidejection head. More specifically, FIG. 26A is a schematic perspectiveview of the liquid ejection head and FIG. 26B is an exploded schematicperspective view of the liquid ejection head. On the other hand, FIGS.27A and 27B are schematic illustrations of adjacently located recordingelement boards. More specifically, FIG. 27A is a schematic top view ofthe liquid ejection head and FIG. 27B is a schematic cross sectionalview taken along line 27B-27B in FIG. 27A.

As illustrated in FIGS. 26A and 26B and FIGS. 27A and 27B, the liquidejection head of this embodiment differs from the liquid ejection headof the first embodiment in that a lid member 20 is arranged between therecording element boards 10 and the support members 30. Additionally, inthe liquid ejection head of this embodiment, a back side supply channel420 for supplying liquid to the ejection ports 13 of each recordingelement board 10 is arranged on the rear surface of the recordingelement board 10 and the lid member 20 operates as lid for the back sidesupply channels 420 of the recording element boards 10. Furthermore, thelid member 20 is provided with supply ports 17 a for supplying liquid tothe back side supply channels 420. The supply ports 17 a are typicallymade to communicate with the supply channels arranged in the insides ofthe support members 30. The lid member 20 is made of resin film and hasa thickness smaller than the thickness of the support members 30. Thethickness of the lid member 20 is preferably not more than 1 mm, morepreferably not more than 0.1 mm.

In the liquid ejection head 3 of this embodiment, ejection ports 13 areformed in the parts of each recording element board 10 that projectoutwardly from the respective edges of the corresponding support member30. Since the back side supply channels 420 are covered by the lidmember 20, liquid can be supplied to the ejection ports 13 in theoutwardly projecting parts of the recording element boards 10.

As in the description of the first embodiment, assume here that one oftwo adjacently located recording element boards 10 will be referred toas the first recording element board and the other will be referred toas the second recording element board and that the support member 30that supports the first recording element board will be referred to asthe first support member and the support member 30 that supports thesecond recording element board will be referred to as the second supportmember. Note that the lid member 20 is arranged between the firstrecording element boards and the respective support members along withthe back side supply channels 420 formed on the surfaces of the firstrecording element boards located close to the respective first supportmembers as supply channels for supplying liquid to the recordingelements to cover the back side supply channels 420.

Note that the lid member that is the lid covering the back side supplychannels 420 is a member having a thickness smaller than the thicknessof the support members 30 so that it can be processed with a degree ofprocess accuracy substantially equal to that of the recording elementboards 10. For example, the lid member 20 can be formed by processing asilicon substrate. If so, the thickness of the lid member 20 can be madeto be not greater than 1 mm. Silicon substrates can be processed bymeans of lithography, blade dicing which is a technique for processingwafers, or laser. Any of these techniques can ensure a degree ofprocessing accuracy substantially equal to that of processing recordingelement boards 10. Alternatively, the lid member 20 can be formed byprocessing resin film. If such is the case, the thickness of the lidmember 20 can be made to be not less than 0.1 mm. Resin film can beprocessed by means of lithography, blade dicing for processing wafers,or laser as in the case of processing silicon substrates. Any of thesetechniques can also ensure a degree of processing accuracy substantiallyequal to that of processing recording element boards 10. The recordingelement boards 10 and the lid member 20 are preferably bonded to eachother without using any liquid adhesive agent. Then, the adhesive agentthat is used to bond the recording element boards 10 and the lid member20 can effectively be prevented from penetrating into the supplychannels in the recording element boards 10 and the lid member 20.

In this embodiment, ejection ports 13 are arranged on the parts of therecording element boards 10 that respectively project outwardly from theedges 413 of the corresponding support member 30. Due to thisarrangement, the distance separating the ejection ports 13 of any twoadjacently located recording element boards 10 of this embodiment can befurther reduced if compared with the first embodiment. Then as a result,the displacement width of the rows of ejection ports in a neighboringarea of any two adjacently located recording element boards 10 can befurther reduced.

Consider an instance where the inter-element distance 404 between twoadjacently located recording element boards 10 is 0.02 mm and aninstance where the inter-element distance 404 between two adjacentlylocated recording element boards 10 is 0.2 mm as in the abovedescription of the first embodiment. In these instances, ejection ports13 are arranged at respective positions separated by 0.05 mm from anedge of a recording element board 10. When the angle formed by twoobliquely disposed sides of each recording element board 10 is 45degrees, the displacement width of two adjacent rows of ejection portswill be respectively about 0.17 mm and about 0.42 mm. Thus, if comparedwith the first embodiment, the displacement width can remarkably bereduced. As described above, the displacement width of this embodimentdoes not depend on the processing accuracy and the mounting alignmentaccuracy of the support members 30. Thus, the displacement width of anytwo adjacently located recording element boards 10 in a neighboring areathereof as viewed in the direction of scanning direction of thecorresponding recording mediums 2 can be reduced to thereby reduce thedisplacement width 403 of rows of ejection ports. Then, as a result,problems such as unevenness of images at positions corresponding toneighboring areas of recording element boards 10 can be minimized andhigh quality images can be produced.

Additionally, as in the first embodiment, the problem that the adhesiveagent bonding the recording element boards 10 and the support members 30creeps up to the first surfaces of the recording element boards 10 whereejection ports 13 are arranged from the gaps 410 separating any twoadjacently located recording element boards 10 can effectively besuppressed.

Note here that ejection ports 13 can be arranged on the parts of therecording element boards 10 that project outwardly from the respectiveedges of the support members 30 also in the first embodiment as in thisembodiment. If such is the case, supply channels need to be formed onthe surfaces of the recording element boards 10 where ejection ports 13are formed in order to supply liquid to the ejection ports 13 arrangedon the outwardly projecting parts of the recording element boards 10.Then, however, while the height of the supply channels is maximallyseveral tens of μm in the first embodiment, the height of the back sidesupply channels 420 of the second embodiment can be made to be aboutseveral hundreds of μm. This means that liquid can more sufficiently besupplied to the ejection ports 13 arranged in the parts of the recordingelement boards 10 projecting outwardly from the corresponding edges ofthe respective support members 30 in the second embodiment than in thefirst embodiment so that the image quality of the areas of the recordedimage that correspond to the neighboring areas can be improved moresatisfactorily in the second embodiment than in the first embodiment.

The rear surfaces where the back side supply channels 420 are formedrefers to the substantive rear surfaces of the recording element boards10 relative to the surfaces thereof where ejection ports 13 are formed.In other words, in an instance where a recording element board 10 isformed by sequentially laying a plurality of substrates one on theother, the rear surface is not the rear surface of the top substrate onthe front surface of which ejection ports 13 are formed but the rearsurface of the entire recording element board 10 produced after layingthe substrates one after another and located opposite to the frontsurface where ejection ports 13 are formed. The distance between twoadjacently located recording element boards 10 is equal to the distancebetween two adjacently located lid members 20 in the instance of FIG.27B, the distance between two adjacently located recording elementboards 10 may well be smaller than the distance between two adjacentlylocated lid members 20.

(The manufacturing steps of the liquid ejection head of the secondembodiment)

FIG. 28 is a flowchart illustrating the manufacturing steps of theliquid ejection head of the second embodiment.

Firstly, an ejection port forming step of forming ejection ports 13 onrecording element boards 10 where circuits such as recording elements 15necessary for bubbling liquid have been formed is executed (Step S501).At this time, the recording element boards 10 are in the form of awafer. Subsequently, a back side supply channel forming step of formingback side supply channels 420 on the back surfaces of the recordingelement boards 10 is executed (Step S502). Then, a lid member formingstep of forming a lid member 20 on the back surfaces of the recordingelement boards 10 is executed (Step S503). Thereafter, a cutting step ofprocessing the recording element boards 10 to make them represent thedesigned proper outer profile and producing recording element boards 10in the form of chips out of the recording element boards 10 in the formof wafer is executed (Step S504). Subsequently, a bonding step ofbonding the recording element boards 10 to the respective supportmembers 30 such that the lid member 20 is located vis-à-vis the supportmembers 30 (Step S505). Finally, an arranging step of arranging thesupport members 30 to which the recording element boards 10 have beenbonded side by side on a flow channel forming member 210 is executed(Step S506).

The liquid ejection head of the second embodiment is produced as a lidmember 20 is formed on the rear surface of the recording element boards10 in the lid member forming step (Step S503) prior to the bonding step(Step S505). Therefore, the displacement width of any two adjacentlylocated recording element boards 10 can be reduced in the scanningdirection to thereby reduce the displacement width of rows of ejectionports without depending on the processing accuracy and the mountingalignment accuracy of the support members 30. Then, as a result,problems such as unevenness of images at positions corresponding toneighboring areas of recording element boards 10 can be minimized andhigh quality images can be produced.

When the lid member 20 is formed by using a silicon substrate, a lidmember 20 formed by using a silicon substrate in the form of a wafer canbe bonded to recording element boards 10 in the form of a wafer.Therefore, the number of steps can be reduced if compared with aninstance where lid members 20 are bonded to respective recording elementboards 10 that are in the form of so many chips.

When the lid members 20 is formed by using resin film, the lid member 20that is in the form film can be bonded to the wafer of recording elementboards 10 to produce a laminate. Then, as a result, the number of stepscan be reduced if compared with the instance of bonding individual lidmembers 20 respectively to recording element boards 10 on a chip by chipbasis just like the above description of forming lid members 20 by asilicon substrate.

Note that the manufacturing steps described for this embodiment is onlyexemplar manufacturing steps and the present invention is by no meanslimited to the above-described manufacturing steps. For example, thesequence of executing an ejection port forming step (Step S501), a backside supply channel forming step (Step S502), a lid member forming step(Step S503) and a cutting step (Step S504) may not necessarily be theone described above for this embodiment. The only requirement to besatisfied for the manufacturing steps is that a lid member forming step(Step S503) needs to be executed before a bonding step (Step S505).

A liquid ejection head 3 and a recording apparatus 1000 as describedabove in detail can find applications in the field of printers, copyingmachines, facsimile machines equipped with a telecommunication systemand word processors having a printer section. Furthermore, a liquidejection head 3 and a recording apparatus 1000 according to the presentinvention can also find applications in the field of industrialrecording apparatus formed by combining various processing devices in acomplex way. For example, they can find applications in the field ofproducing biochips, in the field of electronic circuit printing and soon.

Thus, according to the present invention, the edges of the recordingelement board project outwardly from the edges of the support membersupporting the respective recording element boards in the direction inwhich the support members are arranged side by side. Due to thisarrangement, the distance between any two adjacently located recordingelement boards can be defined by referring to the processing accuracyand the mounting alignment accuracy of recording element boards that arehigher than the processing accuracy and the mounting alignment accuracyof support members. Then, as a result the distance between any twoadjacently located recording element boards can be reduced.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2016-002944, filed Jan. 8, 2016, and Japanese Patent Application No.2016-236639, filed Dec. 6, 2016, which are hereby incorporated byreference herein in their entirety.

What is claimed is:
 1. A liquid ejection head comprising: first andsecond recording element boards having recording elements for generatingenergy to be utilized for ejection of liquid; first and second supportmembers for respectively supporting the first and second recordingelement boards; and a flow channel forming member carrying thereon thefirst and second support members arranged side by side, wherein the edgeof the first recording element board located at the side of the secondrecording element board projects toward the second recording elementboard from the edge of the first support member located at the side ofthe second support member, and wherein a liquid supply channel is formedon the surface of the first recording element board located vis-à-visthe first support member to supply liquid to the recording elements anda lid member is arranged between the first recording element board andthe first support member to form part of the liquid supply channel. 2.The liquid ejection head according to claim 1, wherein the edge of thesecond recording element board located at the side of the firstrecording element board projects toward the first recording elementboard from the edge of the second support member located at the side ofthe first support member.
 3. The liquid ejection head according to claim1, wherein the lid member has a thickness smaller than the thickness ofthe first support member.
 4. The liquid ejection head according to claim1, wherein the thickness of the lid member is not more than 1 mm.
 5. Theliquid ejection head according to claim 1, wherein the lid member isformed by using resin film.
 6. The liquid ejection head according toclaim 1, wherein the first recording element board includes an ejectionport forming member having ejection ports for ejecting liquid and asubstrate having the recording elements, and the substrate has on therear surface thereof, located oppositely from the surface carrying therecording elements arranged thereon, a liquid supply channel forsupplying liquid to the recording elements and a liquid collectionchannel for collecting liquid from the recording elements.
 7. The liquidejection head according to claim 1, wherein the circumferential profilesof the first and second recording element boards are parallelogrammic.8. The liquid ejection head according to claim 7, wherein the edge ofthe first recording element board contiguous to the edge located at theside of the second recording element board does not project relative tothe corresponding edge of the first support member.
 9. The liquidejection head according to claim 1, wherein the liquid ejection head isa page wide type liquid ejection head, and a common supply channel forsupplying liquid to the first and second recording element boards and acommon collection channel for collecting liquid from the first andsecond recording element boards are arranged at the flow channel formingmember.
 10. The liquid ejection head according to claim 1, wherein thefirst recording element board includes an ejection port forming memberhaving ejection ports for ejecting liquid and a substrate having therecording elements, and the processing accuracy of the substrate of thefirst recording element board is higher than the processing accuracy ofthe first support member.
 11. The liquid ejection head according toclaim 1, wherein ejection ports for ejecting liquid are formed at aprojecting part of the first recording element board.
 12. The liquidejection head according to claim 1, wherein a plurality of recordingelement boards including the first and second recording element boardsare linearly arranged on the flow channel forming member.
 13. The liquidejection head according to claim 1, wherein the first recording elementboard has pressure chambers respectively having the recording elementsin the inside thereof and the liquid in the pressure chambers iscirculated between the inside and the outside of the pressure chambers.14. A liquid ejection device comprising a liquid ejection head andsupply means for supplying liquid to the liquid ejection head, theliquid ejection head comprising: first and second recording elementboards having recording elements for generating energy to be utilizedfor ejection of the liquid; first and second support members forrespectively supporting the first and second recording element boards;and a flow channel forming member carrying thereon the first and secondsupport members arranged side by side, wherein the edge of the firstrecording element board located at the side of the second recordingelement board projects toward the second recording element board fromthe edge of the first support member located at the side of the secondsupport member, and wherein a liquid supply channel is formed on thesurface of the first recording element board located vis-à-vis the firstsupport member to supply liquid to the recording elements and a lidmember is arranged between the first recording element board and thefirst support member to form part of the liquid supply channel.
 15. Aliquid ejection head comprising: first and second recording elementboards having recording elements for generating energy to be utilizedfor ejection of liquid; first and second support members forrespectively supporting the first and second recording element boards;and a flow channel forming member carrying thereon the first and secondsupport members arranged side by side, wherein the edge of the firstrecording element board located at the side of the second recordingelement board projects toward the second recording element board fromthe edge of the first support member located at the side of the secondsupport member, wherein the circumferential profiles of the first andsecond recording element boards are parallelogrammic.
 16. The liquidejection head according to claim 15, wherein the edge of the secondrecording element board located at the side of the first recordingelement board projects toward the first recording element board from theedge of the second support member located at the side of the firstsupport member.
 17. The liquid ejection head according to claim 15,wherein the first recording element board includes an ejection portforming member having ejection ports for ejecting liquid and a substratehaving the recording elements, and the substrate has on the rear surfacethereof, located oppositely from the surface carrying the recordingelements arranged thereon, a liquid supply channel for supplying liquidto the recording elements and a liquid collection channel for collectingliquid from the recording elements.
 18. The liquid ejection headaccording to claim 15, wherein the edge of the first recording elementboard contiguous to the edge located at the side of the second recordingelement board does not project relative to the corresponding edge of thefirst support member.
 19. The liquid ejection head according to claim15, wherein the liquid ejection head is a page wide type liquid ejectionhead, and a common supply channel for supplying liquid to the first andsecond recording element boards and a common collection channel forcollecting liquid from the first and second recording element boards arearranged at the flow channel forming member.
 20. The liquid ejectionhead according to claim 15, wherein the first recording element boardincludes an ejection port forming member having ejection ports forejecting liquid and a substrate having the recording elements, and theprocessing accuracy of the substrate of the first recording elementboard is higher than the processing accuracy of the first supportmember.
 21. The liquid ejection head according to claim 15, whereinejection ports for ejecting liquid are formed at a projecting part ofthe first recording element board.
 22. The liquid ejection headaccording to claim 15, wherein a plurality of recording element boardsincluding the first and second recording element boards are linearlyarranged on the flow channel forming member.
 23. The liquid ejectionhead according to claim 15, wherein the first recording element boardhas pressure chambers respectively having the recording elements in theinside thereof and the liquid in the pressure chambers is circulatedbetween the inside and the outside of the pressure chambers.
 24. Aliquid ejection device comprising a liquid ejection head and supplymeans for supplying liquid to the liquid ejection head, the liquidejection head comprising: first and second recording element boardshaving recording elements for generating energy to be utilized forejection of the liquid; first and second support members forrespectively supporting the first and second recording element boards;and a flow channel forming member carrying thereon the first and secondsupport members arranged side by side, wherein the edge of the firstrecording element board located at the side of the second recordingelement board projects toward the second recording element board fromthe edge of the first support member located at the side of the secondsupport member, and wherein the circumferential profiles of the firstand second recording element boards are parallelogrammic.